Hair is comprised primarily of keratin, a polyamide cross-linked by disulfide bonds. The disulfide bonds are responsible for the hair being maintained in a particular configuration.
Permanent waving is a common technique of styling hair by permanently forming or setting the hair into a desired configuration. Cold permanent waving of hair has been a popular means for waving hair since the 1930's. This popularity is due to the greater convenience of this method over other methods in which externally applied heat is needed to achieve the desired result. This additional convenience has permitted nonprofessionals to wave their hair in their own homes.
In cold waving, a reducing agent is applied to the hair, causing the hair to be "softened," i.e., the disulfide linkages present in the keratin are broken. This reducing step may be done after sectioning hair into individual tresses, but before rolling it onto curlers, after the rolling has been accomplished, or at both times. After sufficient time has elapsed, the hair is rinsed and neutralized by chemical or air oxidation, reforming the disulfide linkages broken in the reducing step.
Cold permanent waving is not without is problems, however. The materials are often difficult to use and the desired result is not always achieved. The ends of the hair present handling problems and hair damage is common. In the process, the free ends of the hair must be wound about a cylindrical body, a curler, and this presents some difficulty. To overcome this problem, most commercial waving kits contain small square or rectangular pieces of paper or other material known as end wraps which are folded and placed around a hair tress so as to embrace the free end of the tress.
Among materials used for end wraps are permeable polyester and polyether polyurethanes as disclosed by Haefele in U.S. Pat. No. 3,345,993; impermeable polyester and polyether polyurethanes as disclosed by Haefele in U.S. Pat. No. 3,465,759; and paper as disclosed by Bonilla in U.S. Pat. No. 2,991,790.
The Bonilla patent discloses treatment of end wraps with chemical agents so that the waving solution is counteracted before reaching the hair ends. Treatment of end wraps with citric acid to counteract the waving solution and thereby protect hair ends is also known in the art.
There is, however, a continuing need to simplify the waving process. This object is achieved in the current invention by providing chemically modified end wraps.